A simple spectrophotometric method to determine phytic acid in poultry wastewater without acid digestion

Abstract

ABSTRACT Frequently, wastewater from treatment plants associated with animal husbandry, mainly animal feeding operations, are used to irrigate near agricultural lands based on nitrogen requirements. To avoid soil phosphorus accumulation owing to its long-term application, it is necessary to achieve lower levels of total phosphorus; one of the methods involve eliminating dissolved organic phosphorus (DOP) in treatment systems. The DOP in effluents and manure wastewater streams is commonly quantified without the identification of individual phosphorus species. Nevertheless, characterisation of the DOP is particularly important, because removal techniques, as well as soil sorption capacity and phosphorus transfer in the runoff to water bodies, differ for different DOP compounds. Particularly, phytic acid (PA), the main DOP compound in animal wastes, can strongly bind to soils making it unavailable for plant uptake. This work evaluates the application of a simple analytical procedure to the determination of the PA concentration in manure wastewater. The method does not require a prior acid digestion stage; in addition, sample colour removal, as well as the removal of potentially interfering compounds are not required. The results are in agreement with results obtained using 31P NMR. PA recoveries ranged between 87% and 97%, relative standard deviation was <8.5%, while the limits of detection and quantification for phosphorus as PA were 0.18 mg·L−1 and 0.55 mg·L−1 respectively.